1. Field of the Invention
The invention relates to a ceramic membrane reactor for contacting two reactant gases at different pressures when separated by an oxygen permeable membrane to produce syngas.
2. Background of the Invention
There is considerable interest in converting natural gas, which is mainly methane, into syngas (CO and H.sub.2) which can be further converted into liquid fuels or other valuable chemicals. One process involves reacting oxygen from an oxygen containing gas stream with a hydrocarbon compound in another gas stream without diluting the hydrocarbon or products of oxidation with other gases from the oxygen containing gas stream such as nitrogen from an air stream.
The partial oxidation of natural gas to produce syngas requires an oxygen plant which makes the cost prohibitive in most situations. One way around this is to use a ceramic oxygen separating membrane which will allow atmospheric oxygen to permeate through the membrane while excluding other gases. In a syngas plant, a reactor made of this ceramic material would transport oxygen from the side in contact with atmospheric air to the other side in contact with the natural gas.
Natural gas, as it comes from the well head is at considerable pressure, i.e. around 500-1500 psi. Since ceramic membranes can fracture under pressure, it is necessary to either offset the high pressure gas on one side of the membrane with high pressure air on the other side of the membrane or to reduce the pressure of the gas to match the pressure of the air in order to prevent membrane failure. When the ceramic membrane is subjected to a compressive pressure, i.e. an external force, then the membrane maintains its integrity. High pressure air requires an expensive air compressor which negates the advantage of operating without a cryogenic oxygen separation plant. Depressurizing the natural gas would be a disadvantage since after the syngas is produced it would have to be repressurized for further processing to value added products.